Tumor-specific delivery of drugs for diagnosis and treatment of cancer is an active area of investigations in both experimental and clinical trials (Shukla, G. S. et al. Expert. Opin. Biol. Ther. 2006; 6:39-54). Receptors over expressed on tumor cells or tumor endothelial cells are often exploited for killing tumor cells by selective delivery of potent cytotoxic drugs to either tumor or tumor vasculatures or both (Vyas, S. P. et al. Crit. Rev. Ther. Drug Carrier Syst. 2001; 18:1-76). Examples of such receptors are integrin receptors and α/β heterodimeric transmembrane glycoprotein receptors (the primary cell-adhesion molecules). These receptors are over expressed on the surface of tumor endothelial cells and many tumor cells whereas their degree of expression in pre-existing resting endothelial cells and normal tissues is minimal (Desgrosellier, J. S. Nat. Rev. Cancer 2010; 10:9-22). Because of these reasons, integrin receptor mediated delivery of potent cytotoxic drugs/genes to tumors and tumor endothelial cells is an emerging therapeutic approach for inhibiting tumor growth (Kuldo, J. M. et al. Current Vascular Pharmacology 2005; 3:11-39). For instance, recent studies have shown that integrin targeted RGD-functionalized nanoparticles can deliver anti-cancer drugs selectively to tumor sites (Aniket, S. et al. Acta Biomaterialia 2012; 8:2996-3004, Danhier, F. et al. J. Control Release. 2009; 140:166). Lipopeptides containing a non-cyclic, conformationally unstained simple RGDK and RGDGWK peptide sequence in their polar head-group region can also selectively target genes to tumor vasculature via proangiogenic α5β1 integrin receptors (Pramanik, D. et al. J. Med. Chem. 2008; 51:7298-7302, Samanta, S. et al. Biomaterials. 2010; 31:1787-1797). Combination of potent chemotherapeutics is often recommended toward enhancing therapeutic efficacies, minimizing drug resistance and alleviating toxic side effects (Jinghua, D. et al. International Journal of Pharmaceutics 2012; 426:193-201). Besides chemotherapy, antiangiogenic cancer therapy is another very promising therapeutic modality for combating cancer. Folkman proposed the concept of anti-angiogenic cancer therapy more than forty years back (Folkman, J. N. Engl. J Med. 1971; 285:1182-1186). Angiogenesis, the sprouting of new blood vessels from pre-existing vessels, is a remarkable feature of tumor growth (Carmeliet, P. Nature, 2005; 438:932). Growing tumors get their oxygen and nutrients from these tumor neovasculatures (newly formed blood vessels around tumor). Folkman envisaged for the first time that inhibition of angiogenesis (i.e. killing of tumor endothelial cells) would shut down oxygen and nutrient supply to tumor cells and in consequence, the tumor cells will die of starvation. Prior study showed that the transcription factor STAT3 (signal transducer and activator of transcription 3) plays pivotal role in angiogenesis through modulating VEGF expression (Niu, G. et al. Oncogene 2002; 21:2000-2008). It also produces immunosuppressive factors such as VEGF, TGFβ, IL-6, IL-10 which, in turn, negatively affect functional maturation of dendritic cells, body's most professional antigen presenting cells (APCs) (Gabrilovich, D. et al. Nature Rev. Immunol. 2004; 4:941-952; Zou, W. Nature Rev. Cancer 2005; 5:263-274). Since angiogenesis, sprouting of new blood vessels (neovasculatures) from existing vessels, is a distinguishing feature of growing tumors, inhibiting tumor-associated angiogenesis is a promising therapeutic modality to combat cancer (Weis, S. M. et al. Nature Medicine 2011; 17:1359-70). Tumor stroma primarily consisting of various extracellular matrix (ECM) components is a key regulator of angiogenic cascade (Campbell, N. E. et al. J. Oncol. 2010; 2010:586905). Sprouting of tumor neovasculature critically depends on the interactions between the various ECM components in the tumor stroma and the integrin receptors, the α/β heterodimeric transmembrane glycoprotein receptors (the primary cell-adhesion molecules) expressed on the surface of tumor endothelial cells (Desgrosellier, J. S. et al. Nat. Rev. Cancer 2010; 10:9-22, Folkman, J. Nat. Rev. Drug Discov. 2007; 6(4):273-86, Avraamides, C. J. Nat. Rev. Cancer 2008; 8(8):704-17). An elegant strategy for targeting potent anti-cancer drugs/genes selectively to tumor vasculatures is based on identifying high-affinity integrin receptor ligands through use of phage display libraries under in vivo conditions. Integrins receptor can be internalized by cells on activation with anchoring ligands thereby significantly facilitating the delivery of chemotherapeutics into neoplastic cells and leukocytes when such chemotherapeutics are associated with high affinity ligands for various integrin receptors (Chen, K. et al. Theranostics 2011; 1:189-200). More specifically, immunosuppressive factors inhibit DC maturation by inhibiting expression of MHC class II, co-stimulatory molecules CD80 & CD86 and immune-stimulating molecules, such as tumor-necrosis factor (TNF) and IL-12 (Yu, H. et al. Nature Rev. Immunol. 2007; 7:41-51; Yu, H. et al. Nature Rev. Cancer 2009; 9:798-809). Hence, inhibiting STAT3 signaling pathway is an attractive therapeutic approach for most types of human cancers. WP1066, one of the potent commercially available inhibitors of JAK-STAT pathway, inhibits proliferation and induces apoptosis of cancer cells (Ferrajoli, A. et al. Cancer Res. 2007; 67:11291-11299, Verstovsek, S. et al. Clin. Cancer Res. 2008; 14:788-796). Another efficient method of inhibiting stat3 signaling pathway is based on cleaving stat3mRNA in RNA interference pathway by small non-coding stat3-siRNA (Timofeeva, A. O. et al. PNAS 2013; 110:1267-1272). DNA vaccination, the administration of tumor antigen encoded DNA (capable of inducing both humoral and cellular immune responses), is an emerging therapeutic approach for treatment of cancer (Ishii, K. J. et al. Nature 2008; 451:725-729, Gurunathan, S. et al. Annu. Rev. Immunol. 2000; 18:927-974). A promising approach for enhancing the efficacy of DNA vaccination is based on targeting DNA vaccines to recipients' APCs via mannose receptor, a 180 kDa multi-domains unique transmembrane receptor expressed on the cell surfaces of APCs (Sallusto, F. et al. J. Exp. Med. 1995; 182:389-400). Previously Srinivas, R. et al. demonstrated that liposomes of cationic amphiphiles with mannose-mimicking quinic and shikimic acid head-groups can target DNA vaccines to APCs via mannose receptors by forming electrostatic complexes (lipoplexes) of plasmid DNA encoding melanoma tumor associated antigen (MART1) (Srinivas, R. et al. J. Med. Chem. 2010; 53:1387-1391). Subsequently, Srinivas, R. et al. disclosed development of mannose receptor specific lysinylated cationic amphiphiles with mannose-mimicking shikimic and quinic acid head-groups for use in dendritic cell based genetic immunization (Srinivas, R. et al. Indian Patent Application No. 2170/DEL/2010).
However, there are a number of time-consuming and cost-ineffective steps to be followed in such ex vivo (outside the body cells) DC-transfection based genetic immunization processes. The process involves painstaking isolation of autologous DCs, transfecting them ex vivo with tumor antigen encoded DNA vaccines and reimplanting the ex vivo transfected DCs back into the recipient's body. To this end, Hashida and coworkers reported development of mannose-receptor selective and ultrasound-responsive mannosylated liposomes for direct in vivo transduction of DCs in genetic immunization (Un K. et al. Biomaterials 2010; 31: 7813-7826; Un K. et al. Mol Pharm 2011; 8: 543-554). Most recently, Garu, A. et al. has disclosed that direct in vivo immunization of mice with electrostatic complexes (lipoplexes) of p-CMV-gp100 and p-CMV-tyrosinase (DNA vaccines encoding melanoma tumor antigens gp-100 & tyrosinase, respectively) and liposome of lysinylated cationic amphiphiles with both guanidine and mannose-mimicking shikimic acid head-groups is capable of providing long-lasting (100 days post tumor challenge) tumor protection against aggressive melanoma tumor challenge in immunized mice (Indian Patent Application No. 0017/DEL/2013). Although inhibiting growth of melanoma tumor in mice priorly immunized with such direct in vivo DC-targeting liposomal DNA vaccine formulation was possible, this approach failed to regress established tumor.
Anticancer drugs commonly used for treating several malignant tumors unfortunately are also associated with multidrug resistance (MDR), acute toxicities, cumulative dose-limiting cytoxicity, etc. Thus, there is an urgent need to use combination of chemotherapeutics toward alleviating chemoresistance and improving drug-efficacy (Szakacs, G. et al. Nat. Rev. Drug Discov. 2006; 5:219-234).